On 2014-02-03 04:06:00 +0000, Walter Bright <[email protected]> said:
For starters, grep through the source code for all the implicit
conversions. Then think about how it fits in with match levels,
function overloading, template overloading, partial ordering, ?:,
covariance, contravariance, name mangling, TypeInfo, default
initialization, will general functions have to be written twice (once
for T, again for T?), auto function returns, and that's just off the
top of my head.
It's not just writing a truth table and throwing it over the wall.
But wouldn't that prevent all function arguments from being null at
all? As well as function return values? That'll make it almost
impossible to port existing code to this new D model, or interface with
existing C functions.
It'd still be possible, because you could always use a struct to pass a
@nullable pointer around, but then that struct will not work with
partial ordering, ?:, covariance, and contravariance, making things
quite annoying (just like Rebindable is for tail const/immutable
classes).
As for writing functions twice, I don't see it. T is implicitly
convertible to T?, so a single function with a T? parameter will work
with both T and T? arguments.
--
Michel Fortin
[email protected]
http://michelf.ca
